Andrew III the Venetian was King of Hungary and Croatia between 1290 and 1301. His father, Stephen the Posthumous, was the posthumous son of Andrew II of Hungary although Stephen's older half brothers considered him a bastard. Andrew grew up in Venice, and first arrived in Hungary upon the invitation of a rebellious baron, Ivan Kőszegi, in 1278. Kőszegi tried to play Andrew off against Ladislaus IV of Hungary, but the conspiracy collapsed and Andrew returned to Venice.

Ivan Kőszegi was an influential lord in the Kingdom of Hungary at the turn of the 13th and 14th centuries. Earlier historiographical works also refer to him Ivan Németújvári. He was Palatine in 1281, between 1287 and 1288, and from 1302 until 1307, Ban of Slavonia in 1275, from 1284 until 1285 and in 1290, and Master of the treasury in 1276 and 1291.